scientifiques ennuyeux -> I'd swap boring with "à la con", just for the fun of it

une casse -> that typo turned the crate into a scrapyard

L’ont bourré -> past participle again (la caisse)

fichés dans une casse étiquetée -> what's with this scrapyard, already?
"fiché" could mean "stuck" (like an arrow into a target) or "on a (police) record". When "ficher" is used as an expletive for "foutre", the past participle is "fichu" (mimicking "foutu"). However, it's a bit too mild for the general tone. I'd rather use "foutre" here.
"foutus dans une vitrine avec une pancarte..."

Great thanks! I'd actually picked up a couple of my sillier errors in the meantime but there's still plenty for me to work through there.

couple of questions before I get stuck in:
I had some doubts about using 'chier' - not due to its harshness, "shat" is very harsh anyway. More that I wasn't sure it could be used transitively like that?

Do you mean drop both words "chaud et" or just the "et"? he does say "hot" in the English but I guess it's pretty apparent it was hot.

Yeah I fixed my "casses" oops!

I went with 'ficher' as I'd ulready used "foutre" once - are there any other good alternatives?

des trucs degueu - does that not take an 's'? Possibly not as it's a shortened word?

"chier" is transitive alright. "(en) chier des briques" is just like "shitting bricks", for instance.
However, I'd say less is more when you want French to sound funny. Too many harsh words and it will just sound gross.

I meant "chaud et" as a whole. It sounds good in English, but not so in French. And as you said it's there more for effect than for semantics.

"fichu" is a bit out of tone, like saying "danged" or "darned" instead of "damned" all of a sudden. I don't find the repetition of "foutu" annoying, it's a very common word in casual French, like "bloody" or "damned" in English.
Still if you want alternatives : "[caisse] à la con" (but that's already used for the scientists) "[caisse] à deux balles", "[caisse] pourrie", "putain de..." (a bit strong maybe), "saloperie de..."

Maybe you could use "putain/saloperie de volcan" at the start to free up "foutu"

I think it's worth keeping the chier though - although I do like the alternative. It's just that it is jarring in English too - the "shat" and "fucking" really do jump out of the song and slap you in the face.

I wasn't quite sure if the "crado" i attached to the volcano should stay or not. And I tried to keep in the ät my lust" near the end. Does it work?

ps - it was more the "foutus dans une caisse/foutus dans une vitrine" that seemed a little be too close together. What do you think?

Était gras comme des loches -> either "On était..." or nothing at all.
The way you avoid repeating half of the words is suited for a more literary register, but here an informal tone works much better.

Et n’aimait -> "et on aimait que..." (same as above)

dégoutait -> dégottait ("dégoter" is like "scrounge up").
"on se dégoûtait des truffes" would mean "we put ourselves off truffles" (with "des truffes" as "from truffles"), which could work in a sense (pig out on truffles), but sounds more odd than funny.

ont foutus dans une caisse -> OK sorry, I had missed this occurrence of "foutus". I see now why you wanted to avoid the repetition.
"balancés" would work fine here
Also "collés dans une vitrine" if you want an alternative to "foutu" 3 lines below.